[type42] Fix new memory leak.

We need to inverse inheritance of FT_GlyphSlot_Internal so that we
have a chance to free the rendered bitmap from the parent slot.

* src/type42/t42objs.c (T42_GlyphSlot_Init): Remove the internal parts
of the child `ttslot' and replace it with the parent structure.
(T42_GlyphSlot_Done): Updated accordingly.

ChangeLog

@@ -1,3 +1,14 @@
+2021-06-12  Alexei Podtelezhnikov  <apodtele@gmail.com>
+
+	[type42] Fix new memory leak.
+
+	We need to inverse inheritance of FT_GlyphSlot_Internal so that we
+	have a chance to free the rendered bitmap from the parent slot.
+
+	* src/type42/t42objs.c (T42_GlyphSlot_Init): Remove the internal parts
+	of the child `ttslot' and replace it with the parent structure.
+	(T42_GlyphSlot_Done): Updated accordingly.
+
 2021-06-12  Werner Lemberg  <wl@gnu.org>
 
 	[psaux] Fix another assertion.

src/type42/t42objs.c

@@ -600,9 +600,9 @@
     }
 
     /* share the loader so that the autohinter can see it */
-    FT_GlyphLoader_Done( t42slot->internal->loader );
-    FT_FREE( t42slot->internal );
-    t42slot->internal = slot->ttslot->internal;
+    FT_GlyphLoader_Done( slot->ttslot->internal->loader );
+    FT_FREE( slot->ttslot->internal );
+    slot->ttslot->internal = t42slot->internal;
 
     return error;
   }
@@ -614,8 +614,8 @@
     T42_GlyphSlot  slot = (T42_GlyphSlot)t42slot;
 
 
+    slot->ttslot->internal = NULL;
     FT_Done_GlyphSlot( slot->ttslot );
-    t42slot->internal = NULL;
   }